Room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles, preparation method and application thereof
Room temperature ferromagnetic triclinic Fe5Se8 nanoparticles were prepared by pulsed laser deposition and high-temperature thermal annealing, which solved the problem that iron selenides do not have room temperature ferromagnetism, improved the activity and stability of the catalyst, and made them suitable for electrocatalysis assisted by alternating magnetic fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-24
- Publication Date
- 2026-03-24
AI Technical Summary
Most existing iron selenides do not exhibit room-temperature ferromagnetism, which limits the application of magnetocaloric technology. The direct synthesis of triclinic Fe5Se8 catalysts is a complex and energy-intensive process.
Using a hybrid target material of iron diselenide and carbon, selenium vacancies and strain engineering are introduced through pulsed laser deposition and vacuum high-temperature thermal annealing to induce the orthorhombic iron diselenide phase transformation into room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles for alternating magnetic field-assisted electrocatalysis.
The transformation of conventional non-magnetic orthorhombic iron diselenide into ferromagnetic triclinic Fe5Se8 was achieved, which improved catalytic activity and stability and enhanced the application efficiency of magnetocaloric technology.
Smart Images
Figure CN118324099B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of electrocatalysis, and particularly relates to a room-temperature ferromagnetic triclinic Fe5Se8 nanoparticle and a preparation method and application thereof. BACKGROUND
[0002] The increasing demand for hydrogen energy has prompted researchers to continuously explore clean and efficient strategies to achieve the development and modification of electrocatalysts for hydrogen evolution reaction. As a new technology in the field of energy conversion and storage, the magnetic field assisted electrocatalysis strategy can generate a magnetic heating effect on the surface of the magnetic catalyst, effectively adjust the activation energy and improve the mass transfer, thereby significantly improving the overall activity, and is expected to overcome the limitations in the performance improvement of the current electrocatalyst. Compared with the traditional heating method (heating the electrolytic cell), the magnetic heating effect induced by the alternating magnetic field causes less damage to the electrolytic cell and consumes less energy. Therefore, the coupling of the magnetic catalyst and the alternating magnetic field has become a promising energy-saving strategy, which can greatly improve the performance of the electrocatalyst. As a member of the transition metal chalcogenides, iron selenide has attracted much attention due to its unique electronic structure, rich redox potential and adjustable phase composition. However, most of the iron selenides do not have room-temperature ferromagnetism, which greatly limits the application of the magnetic heating technology. The newly emerging triclinic Fe5Se8 synthesized by chemical vapor deposition shows ferromagnetic order at room temperature, but the formation energy is high and the CVD process is complex. It still faces considerable challenges to directly synthesize the unconventional triclinic Fe5Se8 catalyst. SUMMARY
[0003] The purpose of the present application is to solve the problems of the prior art, and to provide a room-temperature ferromagnetic triclinic Fe5Se8 nanoparticle and a preparation method and application thereof. The following technical solutions are specifically adopted:
[0004] In a first aspect, the present application provides a preparation method of a room-temperature ferromagnetic triclinic Fe5Se8 nanoparticle, comprising the following steps:
[0005] The substrate and the target material are placed on the sample holder and the target holder of the pulsed laser deposition system respectively, and then the target material is ablated by using the excimer laser under vacuum conditions, so that the iron diselenide and carbon in the target material are deposited on the substrate;
[0006] The iron diselenide and carbon deposited on the substrate are placed in an atmosphere filled with selenium powder, heated to 300-400 DEG C for 30-40 s, and then cooled to room temperature for 3-7 min, to obtain non-magnetic orthorhombic iron diselenide nanoparticles;
[0007] Orthorhombic iron diselenide nanoparticles are heated to 700 DEG C-850 DEG C for 70 s-90 s under vacuum conditions, then heat preservation is carried out, and after the heat preservation is completed, cooling to room temperature is carried out, and finally room temperature ferromagnetic triclinic Fe5Se8 nanoparticles are obtained.
[0008] The target material is a mixed target material of an iron diselenide target and a carbon target.
[0009] The application adopts iron diselenide targets and carbon targets as mixed target materials, wherein the orthorhombic iron diselenide is a conventional phase structure of iron selenide, and the introduction of selenium vacancies and strain engineering by rapid thermal annealing treatment in a vacuum environment induces the phase change of the conventional non-magnetic orthorhombic iron diselenide to become the unconventional triclinic Fe5Se8 with ferromagnetism, so that it can be applied to the technology of alternating magnetic field assisted enhanced electrocatalysis, which is very important for improving the catalytic activity and ensuring the efficient application of magnetic heat technology. The selenium vacancies are generated by the evaporation or sublimation of part of selenium atoms in the high-temperature thermal annealing process in the vacuum environment. The introduction of the strain engineering is due to the thermal expansion mismatch between the orthorhombic iron diselenide and the amorphous carbon matrix, so that the volume expansion of the orthorhombic iron diselenide nanoparticles relative to the amorphous carbon matrix produces a large compressive strain.
[0010] As a further preferred embodiment, the vacuum degree under the above-mentioned vacuum condition is 8*10 -7 -5.0*10 -8 Torr. The high vacuum environment can ensure the success of the pulsed laser deposition process and the quality of the nanoparticles.
[0011] As a further preferred embodiment, the above-mentioned excimer laser is a krypton fluoride excimer laser, the wavelength of the excimer laser is 248 nanometers, the energy of the excimer laser ablation target material is 260 mJ-300 mJ, and the time of the excimer laser ablation target material is 3400 s-4200 s. The laser energy and the ablation target material time are crucial for controlling the size and density of the nanoparticles, and too high or too low energy / time that is too long or too short will affect the performance of the final subsequent triclinic Fe5Se8 nanoparticles.
[0012] As a further preferred embodiment, the heat preservation time in the vacuum environment is 7 min-11 min, and the cooling time after the heat preservation is completed is 15 min-25 min. Too long or too short heat preservation and cooling time will affect the size of the nanoparticles, thereby affecting the catalytic performance.
[0013] The second aspect of the application provides a room temperature ferromagnetic triclinic Fe5Se8 nanoparticle prepared by the above-mentioned preparation method.
[0014] The third aspect of the present application also provides an application of the above-mentioned room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles as an electrocatalyst in an alkaline hydrogen evolution reaction.
[0015] The present application has the following beneficial effects: the present application provides room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles, the method realizes phase transition of orthorhombic iron diselenide, converts conventional and easily prepared non-magnetic orthorhombic iron diselenide into unconventional ferromagnetic triclinic Fe5Se8, avoids difficulties such as high formation energy and complex process encountered in direct synthesis, and also provides an application of the room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles in a hydrogen evolution reaction, and the room-temperature ferromagnetic triclinic Fe5Se8 nanoparticle hydrogen evolution reaction electrocatalyst exhibits excellent electrocatalytic activity, good stability and efficient magnetic heat-promoted hydrogen evolution reaction in an alkaline hydrogen evolution reaction. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 XRD patterns of non-magnetic orthorhombic iron diselenide nanoparticles and room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles are shown;
[0017] Figure 2 TEM and corresponding SAED patterns of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles are shown;
[0018] Figure 3 XPS patterns of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles are shown;
[0019] Figure 4 M-H curves of non-magnetic orthorhombic iron diselenide nanoparticles and room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles at a temperature of 300K are shown;
[0020] Figure 5 Polarization curves of non-magnetic orthorhombic iron diselenide nanoparticles and room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles are shown;
[0021] Figure 6 A hydrogen evolution performance testing device and a mechanism schematic diagram are shown with and without an alternating electromagnetic field;
[0022] Figure 7 Polarization curves of non-magnetic orthorhombic iron diselenide nanoparticles and room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles are shown with and without an alternating electromagnetic field;
[0023] Figure 8 A chronoamperometric curve of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles as an electrocatalyst in a constant 20 mA / cm 2 Current density for 20 hours under an alternating electromagnetic field is shown. DETAILED DESCRIPTION
[0024] The following will provide a clear and complete description of the concept, specific structure, and technical effects of the present invention in conjunction with the embodiments and accompanying drawings, so as to fully understand the purpose, solution, and effects of the present invention. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.
[0025] Example 1
[0026] A method for preparing room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles, specifically comprising the following steps:
[0027] (1) The substrate and the target material are placed on the sample holder and the target holder of the pulsed laser deposition system, respectively. The target material is a mixture of three high-purity iron diselenide block targets (99.99%, length × width: 10 × 20 mm) and high-purity carbon circular targets (99.99%, diameter 50 mm) bonded by silver paste.
[0028] (2) Evacuate the growth chamber to a vacuum level of 5.0 × 10⁻⁶. -8 The Torr laser ablated the target material using a 248 nm krypton fluoride (KrF) excimer laser for 3600 seconds with a laser energy of 300 mJ.
[0029] (3) Take out the sample deposited on the substrate and place it in the heating zone of the rapid annealing furnace. In an atmosphere filled with selenium powder, heat it rapidly to 350°C for 35 seconds, then hold it for 5 minutes, and then cool it rapidly to room temperature (about 10 minutes) to obtain non-magnetic orthorhombic iron diselenide nanoparticles confined in amorphous carbon.
[0030] (4) In a vacuum environment, the orthorhombic iron diselenide nanoparticles are heated to 800°C within 80 seconds, kept at that temperature for 10 minutes, and then rapidly cooled to room temperature (about 20 minutes) to obtain room temperature ferromagnetic triclinic Fe5Se8 nanoparticles.
[0031] The relevant characterization data of the above-mentioned room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles are as follows:
[0032] Figure 1 The image shows the XRD patterns of orthorhombic iron diselenide nanoparticles and room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles; Figure 1 It can be seen that the diffraction peaks of the orthorhombic iron diselenide nanoparticles changed significantly after vacuum high-temperature annealing, and perfectly matched the simulated triclinic Fe5Se8 crystal phase. This confirms that the particles have changed from the orthorhombic iron diselenide phase to the triclinic Fe5Se8 crystal phase.
[0033] Figure 2 The image shows the TEM and corresponding SAED images of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles;Figure 2 It can be seen that the Fe5Se8nanoparticles are relatively uniformly distributed in the carbon matrix, with a particle size of ~5.18 nm and a lattice spacing of 0.262 nm, and the crystal face corresponds to the triclinic Fe5Se8(02-2) crystal face.
[0034] Figure 3 XPS diagram of room-temperature ferromagnetic triclinic Fe5Se8nanoparticles is shown; from Figure 3 It can be seen that the element composition and valence state of the triclinic Fe5Se8nanoparticles.
[0035] The triclinic Fe5Se8nanoparticles are prepared by the synergistic effect of selenium vacancies and strain engineering from the conventional and easily prepared orthorhombic iron diselenide, have higher electrical conductivity and faster electron transfer speed, and can exhibit better catalytic activity in hydrogen evolution reaction.
[0036] The room-temperature ferromagnetic triclinic Fe5Se8nanoparticles are subjected to magnetization test, and the process is as follows:
[0037] The test is obtained by using a vibrating sample magnetometer (VSM) in a physical property measurement system (PPMS, EverCool II) to perform magnetization measurement, and the magnetic field is as high as 2 T.
[0038] Figure 4 A graph (M-H curve) of the relationship between the magnetization intensity and the magnetic field of the non-magnetic orthorhombic iron diselenide nanoparticles and the room-temperature ferromagnetic triclinic Fe5Se8nanoparticles at a temperature of 300 K is shown; from Figure 4 It can be seen that due to the influence of thermal disturbance, the triclinic Fe5Se8nanoparticles with magnetic single-domain structure as a whole exhibit superparamagnetic behavior (without coercivity), and the single nanoparticles exhibit ferromagnetic behavior. The orthorhombic iron diselenide nanoparticles exhibit no obvious magnetic hysteresis loop at room temperature, indicating that they have room-temperature non-magnetic property.
[0039] The room-temperature ferromagnetic property of the triclinic Fe5Se8nanoparticles provides conditions for further improving the catalytic performance of the triclinic Fe5Se8nanoparticles by using the magnetic heating effect of alternating magnetic field.
[0040] Example 2
[0041] The hydrogen evolution reaction performance test of the room-temperature ferromagnetic triclinic Fe5Se8nanoparticles is performed, and the specific process is as follows:
[0042] Three-electrode electrochemical tests were carried out in 1 mol / L KOH solution to explore the hydrogen evolution reaction performance of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles; in a three-electrode system, room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles prepared on a glassy carbon substrate by pulsed laser deposition technology combined with rapid annealing were used as a working electrode, a saturated Hg / HgO electrode and a graphite rod were used as a reference electrode and a counter electrode, respectively.
[0043] Figure 5 The polarization curves of non-magnetic orthorhombic FeSe2 nanoparticles and room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles without magnetic heating are shown, and it is shown that the room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles produce 10 mA cm -2 The benchmark current density (equivalent to the current density generated by a 12.3% efficient solar water splitting device) only requires an overpotential of 216 mV, while the non-magnetic orthorhombic FeSe2 nanoparticles require an overpotential of 233 mV, indicating that the room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles after phase transition of the orthorhombic FeSe2 nanoparticles have more excellent hydrogen evolution performance.
[0044] Example 3
[0045] The hydrogen evolution reaction performance of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles was tested with and without alternating electromagnetic fields (the testing device and mechanism are shown in Figure 6 The specific process is as follows:
[0046] A standard three-electrode device was placed in an external coil, and a high-frequency alternating magnetic field (300 kHz) with a certain intensity (4.32 mT) was applied to carry out the electrocatalytic hydrogen evolution reaction experiment.
[0047] Figure 7 The polarization curves of non-magnetic orthorhombic FeSe2 nanoparticles and room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles with and without alternating electromagnetic fields are shown; and it can be seen from Figure 7 that under the action of magnetic heating technology, the catalytic performance of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles is significantly improved, while the catalytic performance of non-magnetic orthorhombic FeSe2 nanoparticles does not change significantly.
[0048] Figure 8 The chronoamperometric curve of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles as an electrocatalyst under alternating electromagnetic fields at a constant current density of 20 mA / cm2 for 20 hours is shown; and it can be seen from Figure 8 that even under the long-term action of alternating magnetic fields, the particles can stably work in alkaline electrolyte for at least 20 hours, and the current density does not change significantly, indicating that the room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles have good electrochemical stability.
[0049] While the description of the application has been presented in considerable detail and particularity with reference to several embodiments thereof, the same is understood to be in no way limiting, as it is contemplated to have the fullest scope of equivalents both as to the form of disclosure and as to equivalents of the disclosed embodiments or any special embodiment thereof, to the full extent that is afforded by the appended claims when interpreted in accordance with the fullest interpretation under the patent statutes and rules that they enjoy. Furthermore, the above description for the application has been presented for the purpose of providing those skilled in the art with a convenient reference. It is understood that various modifications can be made to the present application without departing from the intended scope thereof.
Claims
1. A method for preparing room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles, characterized in that, Includes the following steps: The substrate and target are placed on the sample holder and target holder of the pulsed laser deposition system, respectively. Then, under vacuum conditions, the target is ablated using an excimer laser, so that iron diselenide and carbon in the target are deposited onto the substrate. Iron diselenide and carbon deposited on a substrate were heated to 300 ℃-400 ℃ in an atmosphere filled with selenium powder for 30 s-40 s, held for 3 min-7 min, and then cooled to room temperature for 8 min-11 min to obtain non-magnetic orthorhombic iron diselenide nanoparticles. Under vacuum conditions, orthorhombic iron diselenide nanoparticles were heated to 700 ℃-850 ℃ for 70 s-90 s, then held at that temperature, and finally cooled to room temperature to obtain room temperature ferromagnetic triclinic Fe5Se8 nanoparticles. The target material is a mixture of iron diselenide target and carbon target.
2. The preparation method according to claim 1, characterized in that, The target material is a mixture of iron diselenide block targets and carbon circular targets bonded together with silver paste.
3. The preparation method according to claim 2, characterized in that, The iron diselenide bulk target has a purity of ≥99.99% and a size of 10 mm × 20 mm.
4. The preparation method according to claim 2, characterized in that, The carbon circular target has a purity of ≥99.99% and a diameter of 50mm.
5. The preparation method according to claim 1, characterized in that, The vacuum level under vacuum conditions is 8 × 10⁻⁶. -7 -5.0×10 -8 Entrust.
6. The preparation method according to claim 1, characterized in that, The excimer laser is a krypton fluoride excimer laser with a wavelength of 248 nm. The energy of the excimer laser ablation target is 260 mJ-300 mJ, and the ablation time is 3400 s-4200 s.
7. The preparation method according to claim 1, characterized in that, The heat preservation time in a vacuum environment is 7 min-11 min.
8. The preparation method according to claim 7, characterized in that, The cooling time after the heat preservation is completed is 15 min-25 min.
9. The application of room-temperature ferromagnetic triclinic Fe5Se8 nanoparticles prepared by the preparation method according to any one of claims 1-8 as an electrocatalyst in alkaline hydrogen evolution reaction.